Antishock and microphonism con



May 25, 1954 M. E. wElss 2,679,612

ANTIsHocK AND NICRUPHONISM CONSTRUCTION FOR VACUUM TUBES Filed Sept. 26, 1950 INVENTOR MPT/MEI? E. ivf/5.5

ATTORNEY Patented May 25, 1954 ANTISHOCK AND MICROPHONISM CON- STRUCTION FOR VACUUM TUBES Mortimer E. Weiss, Flushing, N. Y., assigner to Sylvania Electric Products Inc., a corporation of Massachusetts Application September 26, 1950, Serial No. 186,759

1 Claim.

This invention relates to an improved vacuum tube construction affording more rigid support of the electrodes, especially under conditions of shock and vibration. While not limited in its application to tubes of the so-called sub-miniature type, the invention is particularly useful therein because of the unusually severe shock and vibration such tubes may be called upon to withstand.

In many types of vacuum tubes the electrodes are supported and braced by top and bottom mica plates through openings in which the rods, to which the electrodes are secured, pass. It has been proposed in the past to cut the edge of these mica plates or discs with small projections or teeth or with perforations, in such a manner that the over-all diameter of the plates is slightly larger than the interior diameter of the tube envelope. On assembly of the tube, the electrode mount carrying the discs is forced into the tube so that the teeth of the mica plates are in contact with the inside surface of the envelope. The mica is thus sprung slightly at the teeth or adjacent the perforations to resiliently maintain the mount in position within the envelope but under continued vibration or shock, wearing or weakening of the t between mica and envelope may occur permitting vibration of the electrodes.

It is an object of this invention to eliminate or reduce this difficulty and to produce a tube of more rigid construction which will be less subject to disturbances in operation from shock or vibration.

It is a further object of this invention to provide a tube of such improved characteristics which is at least as simple to construct and assemble as the presently manufactured tubes.

Still other objects and advantages of my invention will be apparent from the specification.

The features of novelty which I believe to be characteristic of my invention are set forth with particularity in the appended claim. My invention itself, however, both as to its fundamental principles and as to its particular embodiments will best be understood by reference to the specication and accompanying drawing, in which:

Figure 1 is a longitudinal sectional View of an envelope according to my invention before insertion of the electrode mount, the section being taken on lines I--I of Figure 2.

Figure 2 is a sectional View of the same on lines 2-2 of Figure 1.

Figure 3 is a view similar to Figure l but with the electrode mount in position, and

Figure 4 is a sectional view of the tube of Figure 3 taken on lines 4 4 of Figure 3.

In the embodiment of the invention herein shown and described, which is, for some purposes the preferred embodiment, the envelope I0 is provided with a number of inwardly projecting longitudinal ribs I I. The number of these is not critical but it will generally be desirable to provide at least three spaced 120 apart circumferentially, and they may extend a suihcient length within the envelope to engage either the top or bottom mica disc, or both. Tubing with internal longitudinal ribs formed therein, suitable for envelopes, may be produced by shrinking glass tubing onto a ground mandrel and thereafter removing it from the mandrel.

To assemble the mount in the envelope, the top and bottom mica discs I2 and I3 respectively of the mount are made a littlelarger in diameter than the inside diameter of the envelope at the tips of the ribs, so that the mount has to be slightly forced into final position in the envelope with the mica in pressing engagement with the inner area of the ribs I I. The shape or contour of the ribs as seen in Figures 2 and 4 is not critical, but it will generally be desirable to avoid unduly thin ribs in order to provide a greater area of support between the ribs and the mica. The ribs may, if desired, be slightly tapered so the mount may be more easily inserted in the envelope. The final assembled position is shown in Figures 3 and 4 with the ribs I I supporting the top and bottom mica discs I2 and I3, the electrode I4 between the top and bottom discs and with the leads or electrode supporting rods or wires I5 projecting through openings in the discs.

Without desiring to bind myself to any theory as to why my construction improves the antishock and anti-microphonism characteristics of the tubes, I may say that I believe it is due to the increased area of support of the mica discs afforded by the ribs, and also the increased strength of the mica discs afforded by the elimination of the relatively fragile teeth and the absence of the weakening caused by the perforations.

In this specification I have explained the principles of my invention and the best mode in which I have contemplated applying those principles so as to distinguish my invention from other inventions, and I have particularly pointed out and distinctly claimed the part, improvement or combination which I claim as my invention.

While I have shown and described certain preferred embodiments of my invention, it will be understood that modifications and changes may be made without departing from the spirit and scope thereof, as will be clear to those skilled in the art.

What I claim is:

A new article of manufacture consisting of a vacuum tube having an envelope having inwardly extending longitudinal ribs spaced around the interior thereof, an electrode mount having a. circular insulating disc as a part thereof, portions of the outer edge of said disc being in tightly binding engagement with the interior surfaces of said ribs.

References Cited in the le of this patent UNITED STATES PATENTS 

